Wobble plate drives are used to convert rotary motion to reciprocating motion. The wobble plate drive arm engages the reciprocating spindle. The spindle reciprocates in bearings and the spindle and bearings have had a special non-round cross section so the spindle can be restrained against rotation. This is a costly construction which is very sensitive to wear. In making the cross referenced invention I found I could make the product more compact and less costly by having the drive arm engage the spindle in such a way as to prevent rotation of the spindle.